subject-line-lab SKILL.md skillA
subject-line-lab from aaron-he-zhu/aaron-marketing-skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add aaron-he-zhu/aaron-marketing-skills/subject-line-lab@v20.2.0Pins v20.2.0 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- aaron-he-zhu/aaron-marketing-skills
- Path
email/engage/subject-line-lab/SKILL.md- Versions recorded
- 6
- Latest version
- v20.2.0, committed Oct 29, 2026
- First version recorded
- Jul 24, 2026
- Size
- 14,458 bytes
- Repository stars
- 3,102
- License
- Apache-2.0
Use when the user asks to "generate subject line variants", "pre-score my subject lines", or "will this subject get truncated / trigger spam filters"; produces a labeled subject + preheader variant set and a per-variant heuristic pre-score card — spam-trigger flags, length/truncation across desktop + mobile, emoji-count, and the inbox preview render (from-name + subject + preheader) — before any test is run. Not for the body copy or CTA — use email-creative-builder; not for the A/B test design…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Subject Line Lab Generates a labeled subject-line + preheader variant set and **heuristically pre-scores** each variant — spam-trigger flags, desktop + mobile length/truncation, emoji count, and the rendered inbox preview (from-name + subject + preheader) — so weak candidates are cut *before* they burn a test cell. This is the pre-test bench for the SEND **E (Engagement)** lever: it sharpens the subject/preheader unit that `email-creative-builder` drafts and hands the ranked survivors, each with a stable variant id, to `send-experiment-designer`. **Scope guard**: this skill drafts and pre-scores subject + preheader variants only. It does not write the body copy or CTA ([email-creative-builder](../email-creative-builder/SKILL.md)), design the A/B / send-time test or read out significance ([send-experiment-designer](../../deliver/send-experiment-designer/SKILL.md)), run the full deliverability spam-content scan ([deliverability-qa](../../setup/deliverability-qa/SKILL.md)), or compute any SEND dimension score. The heuristic pre-score is a **flag, never a verdict**: [email-quality-auditor](../../deliver/email-quality-auditor/SKILL.md) owns the profile-weighted EQS and all four… …
Read the whole file at its exact version.
How to install
mdr add aaron-he-zhu/aaron-marketing-skills/subject-line-lab@sha256:15e91857ca4ee597The line at the top of this page pins the label v20.2.0, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_2t6apukgkmh7l4qf)
4 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 6 versions of this file, between Jul 24, 2026 and Oct 29, 2026, about one every 19 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| v20.2.0 latest | 2026-10-29 | 0d0dabf | 14,458 B | A | view · diff |
| v20.1.0 | 2026-09-01 | 0c914b1 | 14,458 B | A | view · diff |
| v20.0.0 | 2026-08-20 | 879002a | 14,458 B | A | view · diff |
| v19.2.0 | 2026-08-10 | d09dd90 | 14,458 B | A | view · diff |
| v19.1.0 | 2026-08-01 | f744424 | 14,458 B | A | view · diff |
| v19.0.0 | 2026-07-24 | 407137c | 14,458 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (14458 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
aaron-he-zhu/aaron-marketing-skills · 3,102 stars · license Apache-2.0 · pushed 2026-11-08 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_2t6apukgkmh7l4qf GET https://markdownregistry.com/api/v1/resolve?ref=aaron-he-zhu/aaron-marketing-skills/subject-line-lab GET https://markdownregistry.com/api/v1/blob/15e91857ca4ee597afc39c090c873eaff3ff3ae4e7db919cb6fd19da8ea1d765
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.
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